Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/nucliweb/webperf-snippets/webperf-medianpx skills add nucliweb/webperf-snippets --skill webperf-mediagit clone --depth 1 https://github.com/nucliweb/webperf-snippetsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/nucliweb/webperf-snippets/webperf-media)<a href="https://agentmods.dev/skills/nucliweb/webperf-snippets/webperf-media"><img src="https://agentmods.dev/badge/skills/nucliweb/webperf-snippets/webperf-media.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00155 | $0.02298 |
| Opus 5 | $0.00077 | $0.01149 |
| Sonnet 5 | $0.00031 | $0.00460 |
| Haiku 4.5 | $0.00015 | $0.00230 |
Grade A, and why
webperf-media scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.
WebPerf: Media Performance
JavaScript snippets for measuring web performance in Chrome DevTools. Execute with mcp__chrome-devtools__evaluate_script, capture output with mcp__chrome-devtools__get_console_message.
Scripts
scripts/Image-Element-Audit.js— Image Element Auditscripts/SVG-Embedded-Bitmap-Analysis.js— SVG Embedded Bitmap Analysisscripts/Video-Element-Audit.js— Video Element Audit
Common Workflows
Complete Media Audit
When the user asks for media optimization or "audit images and videos":
- Image-Element-Audit.js - Analyze all images (format, lazy loading, sizing, fetchpriority)
- Video-Element-Audit.js - Analyze all videos (poster, preload, formats, autoplay)
- SVG-Embedded-Bitmap-Analysis.js - Detect inefficient bitmap images embedded in SVGs
Image Optimization Workflow
When the user asks "optimize images" or "check image performance":
- Image-Element-Audit.js - Full image audit
- Cross-reference with webperf-loading skill:
- Find-Above-The-Fold-Lazy-Loaded-Images.js (incorrectly lazy-loaded images)
- Find-non-Lazy-Loaded-Images-outside-of-the-viewport.js (missing lazy loading)
- Find-Images-With-Lazy-and-Fetchpriority.js (contradictory attributes)
- Priority-Hints-Audit.js (LCP image should have fetchpriority="high")
Video Performance Audit
When the user asks "optimize videos" or "check video performance":
- Video-Element-Audit.js - Full video audit
- Cross-reference with webperf-core-web-vitals skill:
- LCP-Video-Candidate.js (check if video/poster is LCP)
- Cross-reference with webperf-loading skill:
- Priority-Hints-Audit.js (video poster priority)
- Resource-Hints-Validation.js (video preload)
LCP Image Investigation
When LCP is an image and needs optimization:
- Cross-reference with webperf-core-web-vitals skill:
- LCP.js (measure LCP)
- LCP-Image-Entropy.js (analyze image complexity)
- Image-Element-Audit.js - Check format, dimensions, lazy loading
- Cross-reference with webperf-loading skill:
- Find-Above-The-Fold-Lazy-Loaded-Images.js (should NOT be lazy)
- Priority-Hints-Audit.js (should have fetchpriority="high")
- Resource-Hints-Validation.js (consider preload)
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago First seen · 218 lines · 155 tokens per session scan A 40a879e2b617
webperf-media is a skill published in the GitHub repository nucliweb/webperf-snippets (1,445 stars, last pushed 1mo ago), licensed MIT. It adds 155 tokens to every session and 2,298 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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